Each flowchart should ideally begin with a Terminator shape, from which the next step should be linked. Each shape should be indicative of a specific stage in the process and there are conventions for each of these, the most common being the rectangular Process shape. Many others exist, however, including shapes representing Data, Documents and Decisions. Decision shapes are diamonds, each of the four corners (or nodes) being either a link from the preceding shape or action to be taken in the next stage depending on the decision.